Fill in the Blanks

Case of past indefinte tense. Option 1 is wrong as 'did' is followed by the first form of the verb.

Case of present continuous tense. Option 3 is wrong as plural subject takes plural verb.

Demonstrative adjective 'this' leaves no scope for any other option than option 1 to be used here. The 'train' being singular needs a singular verb.

Case of present continuous tense. Option 1 best fits the blank. Options 2 and 3 are wrong as plural subject takes plural auxiliary. Option 4 is also grammatically wrong.

Case of past indefinite tense. Option 2 is wrong as 'did' is followed by the first form of the verb.

Or is the correct conjunction here because it presents an alternative choice between two transportation options (car or auto). Nor requires a preceding negative, and connects items without choice. The context clearly indicates choosing between alternatives.

And is the correct conjunction here because the speaker is asking for both items together (an apple and an orange). Nor requires a negative context, yet shows contrast, and so shows cause - none fit the simple request for two items.

Unless is the correct conjunction because it means if not - the sentence means if you don't know the rules, solving syllogism is tough. If would suggest knowing rules makes it tough (opposite meaning). But and Until don't create the conditional relationship needed.

And is the correct conjunction to show sequential actions - first selling old books, then buying new ones. While could work for simultaneous actions, but doesn't fit the sequence. So shows cause, because shows reason - neither fits the simple sequence of two related actions.

When is the correct conjunction because it refers to a specific point in time (at age nineteen). As suggests reason, during needs a time period not a point, and while suggests duration or simultaneous action - none correctly captures the specific age reference.

Yet is the correct conjunction because it shows contrast - being unwell but still managing to finish work. Therefore shows result (not contrast), while suggests simultaneous action, and so shows cause - none captures the contrast between illness and accomplishment.

The correct answer is 'so' because it shows a cause-effect relationship. Being afraid caused him to run. 'While' and 'and' don't convey this logical connection, and 'that' would change the meaning.

The correct answer is 'so' because it shows the result of not being able to solve the question. 'Because' would reverse the logic (placing the effect first), 'and' merely joins ideas, and 'for' is too formal.

The correct answer is 'yet' because it's commonly used with the present perfect tense ('haven't received') to mean 'so far' or 'up to now.' 'So' and 'and' would leave the sentence incomplete, while 'but' would need a contrasting clause to follow.

The correct answer is 'but' because it shows contrast between wanting to read and not having time. 'Though' would need different sentence structure, 'yet' is less common here, and 'and' doesn't capture the contrast.