誉称“透明金属”的塑料是( )。
A.聚苯乙烯
B.聚氯乙烯
C.聚丙烯
D.聚碳酸脂
参考答案:D
解析:聚碳酸酯誉称“透明金属”,具有优良的综合性能、冲击韧性和延性。
You claim that ______ travelling by boat I am wasting part of my holiday: on the contrary, I regard the sea journey as the most enjoyable part of it.
A.by
B.in
C.since
D.over
尿路感染最常见的感染途径是()
A.上行感染
B.下行感染
C.血性感染
D.淋巴感染
E.直接感染