Rarely _______ so difficult a problem.

Reading became difficult for the old lady, so the optician ______ her a pair of glasses to

There was snow everywhere, so that the shape of things was difficult to______.A．identifyB．

Its an_____difficult problem, which even many professionals cannot work out.A．exceedinglyB

Kissing is so common though we rarely ask why humans touch 【M1】______ their lips together

Its such a difficult problem______no one can work it out.A．asB．thatC．soD．this

This problem is very difficult to deal with. It’s really_______.A、convincingB、seriousC、t