173. One of my Japanese friends sent me two _____, but I didn’t accept them.
| A．jewels | B．jewel | C．jewelry | D．Jewelries |
Many countries, for example, Mexico and Japan, _____a lot of earthquakes.
| A．have | B．having | C．to have | D．having had |
Each of the students, hoping to pass the exam, _____the book.
| A．buying | B．having bought | C．should buy | D．to buy |
He told me the news_____, believe it or not, he had earned $1 000 in a single day.
| A．that | B．which | C．as | D．because |
The research is so designed that once _____ nothing can be done to change it.
| A．begins | B．having begun | C．beginning | D．begun |
If _____ carefully, the experiment will be successful.
| A．do | B．does | C．done | D．doing |