Question

—A number of foreigners       learning Chinese.
—Right. The number of them       increasing little by little.

A．are: is

B．is；is

C．is; are

D．are; are

Answer 1

A

a number of表示许多的意思，故第一个空主语为复数，be用are，the number of表示什么的数量，故第二个空主语为单数第三人称，be用is，故选A。