When he _______ the door, he found his keys were nowhere.
A. would open B. opened C. had opened D. was to open
When he _______ the door, he found his keys were nowhere.
A. would open B. opened C. had opened D. was to open
D
考查非谓语动词。动词不定时的用法。句意为：当他要打开门的时候,他发现他的钥匙不见了。动词不定时表示将要发生的动作。