单选题 We've tested three hundred types of boot, ______ is completely waterproof.
A. no of which B. some of that
C. none of which D. neither of which

【正确答案】 C

【答案解析】[解析] 我们已经测试了三百种靴子了，没有一种是完全防水的。这里空格后是is，单数形式，前面要用否定形式，no of which是错误的，neither是两者选一，只有C正确。