Our math teacher, however, _____ speak English well.
Fujian has shut down the chicken markets ______ human infections of H7N9 were found.
I got to the lecture hall very early, ______ to get a good rest.
It hasn’t been announced ______ the plane is to take off.
Students ______ to do some voluntary work every year.
You can smoke here ______ you leave a window open to let the smoke out.