__________of the land in that district __________ covered with trees and grass．

We had planned to climb the hill this morning, but the heavy rain _____ our plan.

Mr. Wang told us that he would devote all the time he could spend _______ his oral English before going abroad.

 The lack of eco-friendly habits among the public is thought to be a major ____ of global climate change.

We did have a quarrel about money last night, but now we have already _____.