单项选择题
（）is announced in today's papers, the Shanghai Export Commodities Fair is also open on this Sunday.
A．That B．Which C．As D．It
单项选择题 The earth,（）is the fifth largest planet in the solar system, is the third planet from the sun.
单项选择题 We've tested three hundred types of boots, none of（）is completely waterproof.
单项选择题 All（）is needed is a continuous supply of fuel oil.
