Pine trees, of which there are almost one hundred _____, are found throughout the North Temperate Zone.
| A．species | B．samples | C．specimens | D．Standards |
This is the very plan for our May Day holiday _______ was made by our classmates.
| A．which | B． that | C．who | D．what |
Is _____ necessary to take off our shoes when we enter the computer lab?
| A．this | B．it | C．everyone | D．he |
____ matters most in learning English is enough practice.
| A．What | B．Why | C．Where | D．Which |
Only whenin the afternoonable to leave．
| A．the match was over; they were | B．was the match over; were they |
| C．was the match over; they were | D．the match was over; were they |
There are 51 students in Class Three, _____ failed in the test．
| A．all of which | B．all of them | C．none of whom | D．none of them |