Many people the accident so it was not difficult to investigate（调查）.A. witnessedB. yell

问题补充：

Many people the accident, so it was not difficult to investigate（调查）.

A. witnessed

B. yelled

C. annoyed

D. envied

答案：

(答案→)A. witnessed

B. yelled

C. annoyed

D. envied

解析：考察动词。Witness 目击 yell 大叫，叫喊 annoy 使某人生气 envy 嫉妒

句意为，很多人目击了这次事故，因此它不难调查。