单选题：______, Franks never seems to be able to do the work satisfa..

Don’t touch anything in the lab unless____.A. to be allowed B. allowed C, to be allowing D.allowed to

—Will you go fishing with me?—___________.A．No, I'll be very busyB．Yes, I'll be gladC．Certainly, I'll be sorryD．Certainly, I'll be glad to

No sooner ____than it began to rain heavily.[ ]A. the game beganB. had the game beganC. did the game beginD. had the game begun

Only when _______ possible to settle the problem.A．does the editor come will it beB．the editor comes will it be C．has the editor come it will beD．the editor comes it will be

Only by practicing every day ___________ English well.A．can we learnB．we can learnC．did we learnD．learn we