离心式压缩机管路系统法兰连接处,有螺栓紧力不够、垫片失效等现象,封油泄漏,会造成()
A.封油箱液位下降
B.封油压力上升
C.封油温度上升
D.封油温度下降
参考答案:A
—Do you know the boy ____ is playing soccer there?
—Certainly, he is a friend of my _____
A.who; brother’s
B.who; brother
C.whom; brother’s
D.whose; brother
透明质酸在细胞外基质中的存在方式和作用是什么?