Fill in the blank with the correct form of the verb given in the bracket.
The moon has not yet ______. (appear)
(a)Appear
(b)Will have appeared
(c)Would have appeared
(d)Appeared

Hint: Read the given sentence carefully. Try to make out the core meaning of it. Find out the subject, predicate and the object of the given sentence.

Complete answer:The given sentence conveys that the moon isn’t visible yet. We have to fill in the blank with the correct verb form of ‘appear'. The word ‘appear' is a verb.
Now, let us examine all the given options to find out the correct option :
(a)Appear-It is a verb which means ‘to seem’. We have to use a verb in the past tense for the given blank and this is not the suitable answer.
(b)Will have appeared-It is in the future perfect tense and cannot be used in the given blank. So, we will eliminate this option.
(c)Would have appeared-It cannot be the correct answer as the tense is not matching to that of the given sentence. It cannot be used after “yet” in this particular sentence.
(d)Appeared-It is in the past tense and we have to use a verb in the past tense for this particular question. It is suitable for the given blank.
Hence, the correct option is option ‘d'.

Note:All the other options are plausible distractions. You must take care of the tense of the sentence, and fill in the blank with the correct verb form.