________ from space, the earth is blue.
| A．When seeing | B．When see | C．When we see it | D．When to see |
We had better not __ them busy all day long.
| A．to keep | B．keeping | C．kept | D．keep |
The girl is dangerous ___.
| A．to make friends | B．make friends with | C．to make friend with | D．to make friends with |
---Why was Mary so upset? ---She isn't used ___ criticized.
| A．be | B．to be | C．to being | D．being |
Why don't you get your friend __ it to you.
| A．to explain | B．explain | C．explaining v | D．explained |
With the child ___ the way, we had no trouble in finding the house.
| A．to lead | B．had led | C．led | D．leading |