Explanation

Several words are sometimes used as adverbs or sometimes used as prepositions.

A word is a preposition when it governs a noun or a pronoun, It is an adverb when it does not.

Do you want to come in? “In” is an adverb here

Is he in his room? “In” is a preposition here

Explanation

Several words are sometimes used as adverbs or sometimes used as prepositions.

A word is a preposition when it governs a noun or a pronoun, It is an adverb when it does not.

Don’t run around.  “Around” is an adverb here

Don’t loiter around the street. “Around” is a preposition here

Explanation

Suppositional sentences having phrases like “I wish”, He/She wishes”, As if”, As though”, and indicating some unfulfilled wish/desire take simple past.

Explanation

Because down is given at the last of the sentence.