Question

We __________ 1000 English words since we __________ to learn English.

1. A.
   learned; begin
2. B.
   have learning; began
3. C.
   have learn; begun
4. D.
   have been learning; began

Answer 1

D
since 引导的时间状语从句中，当从句中用since+表示一般过去时时，主句要用现在 完成进行时或现在完成进行时，（动词必须是延续性动词）故选D