—Have you heard from Nelly recently?
— Yes, I _________ his letters and cards many times while I was in Italy.
| A．have received | B．received | C．had received | D．would receive |
The school rules state that no child shall be allowed out of the school during the day, __________ accompanied by an adult.
| A．once | B．when | C．if | D．unless |
Now a lot of new technologies can ___________ problems in industry.
| A．be applied to solve | B．be applied to solving |
| C．apply to solve | D．apply to solving |
________ entered the classroom _________ the bell rang.
| A．We hardly had, before | B．Hardly had we, when |
| C．Hardly had we, than | D．Hardly did we, when |
So loudly ______ that every one of the class could hear him.
| A．did he speak | B．did he spoke |
| C．spoke he | D．he spoke |
---What do you think made her so upset?
---_____________ her hometown.
| A．As she missed | B．Missed | C．Because of missing | D．Missing |