will Mr. Green be back? -- In a week I think.A. How oftenB. How manyC. How longD. Ho

问题补充：

-- will Mr. Green be back? -- In a week, I think.

A. How often

B. How many

C. How long

D. How soon

答案：

A. How often

B. How many

C. How long

(答案→)D. How soon

解析：句意: -Mr. Green 多久才能回来？-我想一周后。how often 多久一次，询问做某事的频率；how many 多少，询问数量；how long 多久，对一段时间提问；how soon 多久，多快，常用在一般将来时中。故选D。