---In recent years, problem of global warming had been very serious.
---That is right. People are facing number of natural disasters now.
A. \; a
B. \ ;the
C. the; a
D. a ;a
网友回答
A. \; a
B. \ ;the
(答案→)C. the; a
D. a ;a
解析：考查冠词。第一空使用the特指全球变暖的问题；第二空是固定词组a number of许多，大量；修饰可数名词复数形式。故C正确。