- How long did David work here? - For half a year he didn't leave muchon us.A. expression

问题补充：

- How long did David work here?

- For half a year, he didn leave muchon us.

A. expression

B. instruction

C. conclusion

D. impression

答案：

A. expression

B. instruction

C. conclusion

(答案→)D. impression

解析：考查名词辨析。句意：--大卫在这里工作了多久？--四年半，他没有给我们留下太深的印象。leave an impression on sb给某人留下印象。A表情；B指示，说明；C结论；D印象。故选D。