will the meeting last? -- they reach an agreement.A. How long; Not untilB. When; Not u

问题补充：

-- will the meeting last?

-- they reach an agreement.

A. How long; Not until

B. When; Not until

C. How long; Until

D. When; Until

答案：

A. How long; Not until

B. When; Not until

(答案→)C. How long; Until

D. When; Until

解析：句意：会议要开多久？直到他们达成协议。对一段时间的提问常用疑问词how long；until直到；not…until直到……才，但通常不用not until，所以选C。