Scientists are convinced ___ the positive effect of laughter ____ physical and mental health.
| A．of; on | B．by; in |
| C．of; at | D．on; at |
So much progress _____ in the past few months that she now has no difficulty in making herself understood in English.
| A．did she make | B．has she made | C．she has made | D．she made |
Much to my, I’m unable to accept your kind invitation.
| A．fault | B．duty | C．guide | D．regret |
—Shall we hang out tomorrow morning?
— ________ I’ll save the morning for my homework.
| A．Sorry, I can’t make it. | B．Yes, it’s a good idea. |
| C．Well, it all depends. | D．No, that’s impossible. |
I have been in low spirits ______she left our school
| A．ever before | B．ever so | C．ever since | D．than ever |
We have to ________ the picnic because of the heavy rain.
| A．spend on | B．put off | C．put on | D．look up |