His sister left home in 1998, and _______since. 
| A．had not been heard of | B．has not been heard of |
C．had not heard of | D．has not heard of |
1. Would you please __the paper for me and see if there are any obvious mistakes?
| A．look around | B．look into | C．look up | D．look through |
________ many times , he finally understood it.
| A．Told | B．Telling | C．Having told | D．Having been told |
The teacher together with the students ________ discussing Reading Skills that ________ newly published in America .
| A．are ; were | B．is ; were | C．are ; was | D．is ; was |
—You speak very good French !
—Thanks . I __________ French in Sichuan University for four years.
| A．studied | B．study | C．was studying | D．had studied |
Not until I came home last night ________ to bed .
| A．Mum did go | B．did Mum go | C．went Mum | D．Mum went |