Question 138·Hard·Form, Structure, and Sense
During the past decade, research on microplastics has accelerated dramatically; ______ have the ecological consequences of these particles been investigated at scales ranging from coastal wetlands to the deep sea.
Which choice completes the text so that it conforms to the conventions of Standard English?
For sentence-completion questions on Standard English conventions, first check the punctuation and structure around the blank to see whether you need a full clause or just a phrase. Then, plug in each option and read the sentence out loud in your head, listening for subject–verb agreement, tense consistency, and natural word order. Finally, compare similar-sounding options by asking which one matches common, idiomatic English expressions (like in recent years) and preserves the intended meaning of the sentence.
Hints
Look at the punctuation and clause structure
A semicolon separates two complete sentences. Check what is already provided after the blank and think about what kind of words can come before have the ecological consequences of these particles been investigated... to make a full, correct sentence.
Notice the word ‘only’ and inversion
Three options start with Only. When English sentences start with only plus a time expression, do we usually say Subject + have/has, or do we invert it to have/has + subject?
Test each option in the sentence for grammar
Read the full sentence with each choice. Does any option create a tense or verb mismatch around have been investigated?
Compare the time phrases
Focus on the expressions in recent years, within recent years, and just recent years. Which of these sounds like the usual, natural way to talk about a time period at the start of a sentence?
Step-by-step Explanation
Check what must come after the semicolon
A semicolon must be followed by a complete sentence (an independent clause). The part after the blank is have the ecological consequences of these particles been investigated at scales ranging from coastal wetlands to the deep sea. So whatever fills the blank must combine with this to form a full, grammatically correct clause.
Match the blank to the existing verb phrase
Notice that the verb phrase begins with have been investigated, and the subject is the ecological consequences of these particles. When a sentence begins with a limiting adverb like only, English often uses inversion: instead of the ecological consequences have been investigated only in recent years, we can say Only in recent years have the ecological consequences been investigated. So the blank should be an introductory time phrase that naturally precedes have the ecological consequences....
Eliminate the option that breaks the verb structure
Option A starts It was only in recent years. If you put that into the sentence, you get: ...; It was only in recent years have the ecological consequences been investigated... This mixes was and have incorrectly. With It was only in recent years, the rest would need to change to something like that the ecological consequences... have been investigated, which is not what the sentence has. So A cannot work.
Choose the most idiomatic time phrase with ‘recent years’
The remaining choices all begin with Only plus some form of recent years. We need a natural, prepositional time phrase: we commonly say in recent years, not within recent years, and we do not say Only recent years have the ecological consequences... because that makes recent years the subject. Only one option gives the correct, idiomatic phrase that fits smoothly as Only ___ recent years have the ecological consequences.... That correct choice is D) Only in recent years.