The research is so designed that once __________ nothing can be done to change it.
| A．begins |
| B．having begun |
| C．beginning |
| D．begun |
--- I wonder if I could pay the bill by check.
--- ______. The card machine has just broken down.
| A．No problem | B．Take your time |
| C．Never mind | D．I’m sorry |
Grandma pointed to the hospital and said, “That’s ______ I was born.”
| A．when | B．how | C．why | D．Where |
Is this your necklace, Mary? I ______ it when I was cleaning the bathroom this morning.
| A．came across | B．dealt with |
| C．looked after | D．went for |
_______ the forest park is far away, a lot of tourists visit it every year.
| A．As | B．When |
| C．Even though | D．In case |
Last night, there were millions of people _______ the opening ceremony live on TV.
| A．watch | B．to watch | C．watched | D．Watching |