Question

In the following sentence supply a verb in agreement with its subject.

The ebb and flow of the tides ______ explained by Newton. [Advanced]

• A. Was
• B. Were
• C. Has
• D. Have

Answer 1

The correct option is A Was

'Ebb and flow' is a compound subject with the coordinating conjunction 'and.' Compound subjects joined by 'and' are usually treated as plural and need plural verbs. However, in this sentence, 'ebb and flow' is considered as a single unit or entity, hence it is treated as a singular subject and requires a singular verb. So, the correct option is A) was.
Options C and D do not result in grammatically correct sentences.