He left his hometown in 1990, and great changes _________ ever since.
| A．had taken place | B．took place |
| C．have been take place | D．have taken place |
The two girls are so alike that strangers find________difficult to tell one from the other.
| A．it | B．them | C．her | D．that |
The manager had fallen asleep where he_______，without undressing.
| A．was laying | B．was lying |
| C．had laid | D．had lied |
Give yourself 10% of________is left for your work and let me have the rest.
| A．which | B．that | C．what | D．where |
The school has developed an online system________ students can choose their own teachers.
| A．which | B．when | C．that | D．where |
We should do what we have to do________ we can do what we want to do in the future.
| A．so that | B．in case | C．for fear that | D．now that |