At the class meeting, he made two suggestions, ______ were of great value.
| A．all of them | B．all of which | C．both of them | D．both of which |
The machine has been made easier for it __________.
| A．to operate | B．operated |
| C．being operated | D．to be operated |
No matter how bright a talker you are, there are times when it's better __________ silent.
| A．remain | B．be remaining |
| C．having remained | D．to remain |
I remembered __________ the door before I left the office, but forgot to turn off the lights.
| A．locking | B．to lock |
| C．having locked | D．to have locked |
George returned after the war, only __________ that his wife had left him.
| A．to be told | B．telling |
| C．being told | D．told |
Having finished her project, she was invited by the school __________ to the new students.
| A．speaking | B．having spoken |
| C．to speak | D．to have spoken |