When he the door, he found his keys were nowhere.
| A．would open | B．opened | C．had opened | D．was to open |
______ a good insulator , rubber is often used in cables.
| A．Having been | B．To be | C．Be | D．Being |
Do you mind ______ alone at home?
| A．Jane leaving | B．Jane having left |
| C．Jane’s being left | D．Jane to be left |
______ unless I call you.
| A．Please come | B．Not come in | C．Don’t come in | D．Come in |
_______ about the universe up till now.
| A．So little had me known | B．Only a little do we know |
| C．Very little have we known | D．Little shall we know |
So badly ______ in the accident that he was sent to a hospital.
| A．did he hurt | B．he was hurt | C．was he hurt | D．be did hurt |