题目

Anyone，once________positive for H7N9 flu virus，will receive free medical treatment from our government. A．to be tested                 B．being tested C．tested                       D．to test 答案：C空间中有一条线段PQ的三视图，俯视图是长度为1的线段，侧视图是长度为2的线段，则线段PQ长的取值范围 ．