题目

题型：不详难度：来源：

This is a process          happens when land becomes desert        people cut down trees and dig up grass.

A．when; because

B．that; because of

C．when; because of

D．which; because

答案

D

解析

本题修饰名词process是一个定语从句，关系词用that或which，本题后半句跟的是一个原因状语从句，用because来连接，故本题只能选D。