1. Words that need to start with a vowel after an can only be apple

Two must be followed by a plural noun, so you can only choose C

2. Fixed collocations, memorize them by rote, do more questions, and you will get better at it

3. Meed can be used as an action verb or a modal verb

There is do in the answer sentence Explain that need here is after the action verb + to do sth

4. n't is used directly after need, indicating that it is used as a modal verb here, and action verbs do not have this form

, add the verb base form after the modal verb

worry is a verb and cannot be used directly with the verb be