Select the most appropriate word to fill in the blank.

If only we ______ a light! It is depressing to wait in the dark.

had

The correct word to fill in the blank is had.

The sentence "If only we ______ a light!" is a hypothetical statement, meaning that it is not actually happening. The speaker is expressing a wish or desire for something that is not currently the case. In this case, the speaker wishes that they had a light to make it less depressing to wait in the dark.

The word "had" is the past tense of the verb "have," and it is the most appropriate word to use in this context to express a past wish or desire. The other options are not as appropriate.

• Have is the present tense of the verb "have," and it does not make sense to say "If only we have a light!" in this context, as the speaker is not currently in possession of a light.
• Are having is the present progressive tense of the verb "have," and it does not make sense to say "If only we are having a light!" in this context, as the speaker is not currently experiencing the act of having a light.
• Have had is the past perfect tense of the verb "have," and it can be used to express a past action that happened before another past action. In this context, it would mean that the speaker had a light at some point in the past, but they no longer have it. This is not the meaning that the speaker is trying to convey.