Explanation: Why 'is' is the Winner

This is a perfect example of a **subject-verb agreement** question, a staple in Digital SAT grammar. The main rule is straightforward: singular subjects need singular verbs, and plural subjects need plural verbs.

The SAT tries to trick you by putting extra information between the subject and the verb. Here, the real subject is "The vest frottoir." Even with the description ("a wearable washboard..."), "vest frottoir" is *one single thing*. So, we need a *singular* verb.

• (A) 'have been' is plural. Nope.
• (B) 'is' is singular and present tense. Perfect match for our singular subject "vest frottoir."
• (C) 'were' is plural past tense (or used in specific 'if' clauses). Doesn't fit.
• (D) 'are' is plural. Incorrect.

Key Takeaway: Find the *true subject* first, ignore the fluff in between, then match the verb!

Explanation: Connecting Ideas Correctly

This question tests how well you can connect ideas without creating errors like **comma splices**. Let's analyze the sentence parts:

Part 1 (Independent Clause): "Featuring...paint, Zhang Daqian's...painting... is inspired by the tradition of qinglü shanshui, a type of Chinese landscape painting..." This whole chunk before the blank forms a complete thought (an independent clause).

Part 2 (Descriptive Phrase): "...by the use of blue and green hues..." This part describes the "landscape painting." It *depends* on the first part and cannot be its own sentence.

The Rule: You can't join two independent clauses with just a comma (that's a comma splice!). Since Part 2 is *not* independent, we need an option that creates a *modifying phrase*, not another complete verb that would form a second independent clause.

• (A), (B), (D) - 'has been characterized,' 'will be characterized,' and 'is characterized' all act like main verbs. Using them after the comma would create a comma splice (Independent Clause + Comma + Independent Clause = Error!).
• (C) 'characterized' - Correct! This is a *past participle*. It acts like an adjective here, modifying "painting." It creates a descriptive phrase, correctly linked to the first part of the sentence. You can almost imagine "which is" before it: "...painting, *(which is)* characterized by..." Our sat online coaching often emphasizes recognizing these participle forms.

Key Takeaway: If a comma separates two parts, check if *both* could be sentences. If yes, a comma alone isn't enough. If only the first part is a sentence, the second part needs to modify it, often using participles (-ing or -ed forms).

Explanation: Knowing When to Stop and Start

This question is all about properly separating complete thoughts, also known as **independent clauses**. Let's identify them:

Clause 1: "For centuries, scholars dreamed about locating a copy of this legendary lost work..." (Subject: scholars, Verb: dreamed). This is a complete sentence.

Clause 2: "...That fantasy (partially) became reality in 2022..." (Subject: fantasy, Verb: became). This is also a complete sentence.

Since we have two independent clauses, we need appropriate punctuation between "work" and "That". A comma alone isn't strong enough.

• (A) 'work, that' - Incorrect. Comma splice! You can't join two full sentences with just a comma.
• (B) 'work that' - Incorrect. This creates a run-on sentence, smooshing two complete thoughts together without any punctuation.
• (C) 'work. That' - Correct! A period properly ends the first independent clause. "That" starts the second independent clause, referring back to the "work." This creates two clear, grammatically sound sentences. A good sat study guide will emphasize this rule.
• (D) 'work and that' - Incorrect. You could use ", and" to connect two independent clauses, but there's no comma here. Also, "and" doesn't quite fit the meaning; the second sentence is more of a result.

Key Takeaway: Two independent clauses need strong separation: a period (.), a semicolon (;), or a comma followed by a conjunction (like 'and', 'but', 'so').

Explanation: Handling Introductory Phrases

This sentence starts with a long introductory phrase (a **dependent clause**) that sets the scene:

Dependent Clause (Introductory): "With a blend of traditional design elements... and modern ones, such as floor-to-ceiling windows..." This part *depends* on the rest of the sentence; it can't stand alone.

Independent Clause (Main Idea): "...transitional design splits the difference between old and new, a mixture that is increasingly seen..." (Subject: design, Verb: splits). This part *can* stand alone as a sentence.

The Rule: When a sentence starts with a dependent clause or a long introductory phrase, you generally need a **comma** to separate it from the main independent clause.

• (A) 'windows: transitional' - Incorrect. A colon (:) must follow a *complete* sentence (an independent clause), and the introductory phrase isn't one.
• (B) 'windows—transitional' - Incorrect. Like a colon, a dash (—) used this way typically follows an independent clause. The intro phrase is dependent.
• (C) 'windows. Transitional' - Incorrect. Using a period creates a sentence fragment ("Transitional design splits..."). The first part ("With a blend...") needs to connect to a main clause.
• (D) 'windows, transitional' - Correct! The comma correctly separates the long introductory dependent clause from the main independent clause. "Transitional" acts as an adjective describing "design."

Key Takeaway: Long introductory phrases or dependent clauses at the beginning of a sentence are usually followed by a comma before the main part of the sentence starts.

Explanation: Matching Pronouns to Nouns

This question tests **pronoun agreement**. Pronouns (like 'it', 'they', 'these') must match the noun they refer back to (the *antecedent*) in number (singular or plural).

What "often consists of just one or two suppliers"? The sentence starts by talking about "a given industry..." Although examples ("water and electricity") are mentioned, the main subject being discussed in that first clause is the singular noun "industry."

Therefore, we need a *singular* pronoun to refer back to "industry."

• (A) 'these' is plural. Incorrect.
• (B) 'they' is plural. Incorrect.
• (C) 'it' is singular. Correct! "It" properly refers back to the singular noun "industry."
• (D) 'this' is singular, but 'it' is the more standard and natural pronoun to refer back to a noun like "industry" in this context. "This" often points to something more immediate or abstract. High-quality sat exam study material emphasizes choosing the clearest pronoun.

Key Takeaway: Find the noun the pronoun is replacing (the antecedent). Determine if the noun is singular or plural. Choose the pronoun that matches!