He was convinced on the basis of he had experienced by then that there would be a long and difficult struggle.
| A．why | B．what | C．how | D．which |
“Did Jim come？” “I don’t know. He _______ while I was out.”
| A．might have come | B．might come |
| C．mush have come | D．should have come |
“Look at these tracks. It _______ be a wolf.” “Don’t be so sure. I think it _______ be a fox.”
| A．must; could | B．may; might |
| C．need; must | D．could; need |
“Show me your permit, please.” “Oh, it’s not in my pocket. It ______.”
| A．might fall out | B．could fall out |
| C．should have fallen out | D．must have fallen out |
“Is there a flight to London this evening？” “There _______ be. I’ll phone the airport and find it out.”
| A．must | B．might |
| C．would | D．can |
“You ______ your teacher for help. He is kind-hearted.” “Yes. A whole day _______.”
| A．can ask, will waste |
| B．must have asked, had wasted |
| C．could have asked, was wasted |
| D．shouldn’t have asked, would be wasted |