You have to keep on learning if you want to keep ______ with the development of modern science and technology.

He hadn’t seen his mother for a long time, so when he saw his mother he _____ crying.

—Do you have enough to _____all your daily expenses? ----Oh yes , enough and spare.

After the earthquake, the first thing the local government did was to provide ____________                for the homeless families.

I can't _ him in the knowledge of wild plants．As a matter of fact, he' s an expert．