One day， _____，Newton saw an apple fall from a tree.
| A．to sum up | B．what’s more | C．it is said | D．in addition |
—Did your mother sleep well last night?
—She ______ have slept through all those noises.
| A．mustn't | B．may not |
| C．can't | D．won't |
Don't use water to put out the fire if oil catches fire. As is known, oil ______ float on water.
| A．shall | B．must |
| C．may | D．will |
—Lisa is going traveling at the cost of losing her job.
—Really? She ______ a lot of money.
| A．must save | B．might save |
| C．must have saved | D．might have saved |
—Jenny took the 8:00 bus to Shanghai this morning.
—Really? She ______ the 9:00 train. It's much more comfortable and safer to travel by train.
| A．could have taken | B．should take |
| C．must have taken | D．can take |
Hi, sir. Some students want to see you. ______ they wait here or outside?
| A．Will | B．Shall |
| C．May | D．Can |