下列（）可以获得较高真空度或超高真空度。
A、水蒸气喷射泵
B、水喷射泵
C、油扩散泵和油增压泵
D、空气喷射泵
参考答案：C
Peter has treated himself to too much delicious food， his sharp increase in weight
A．accounting for
B．appealing to
C．bringing in
D．allowing for
肿瘤的硬度与下列哪项无关（）
A.肿瘤的良、恶性
B.肿瘤的种类
C.实质与间质的比例
D.肿瘤间质血管的比例
E.变性、坏死等继发改变
