以下哪项因素与原发性高血压左室后负荷增加有最密切的关系（） A.外周血管阻力增加

We like ______ on Sundays when the whole family get together talking and laughing.[      ]

A. this

B. that               

C. it              

D. those

省际间客运（旅游）班车、货运班车，应按（）的原则执行。

A、先报先批

B、客源流向多的多批

C、平等互利

D、共同经营

第一节短文改错(共10小题；每小题1分，满分10分)

People communicate in words. Do you think you can communicate without words? A smile on your face show you are happy but friendly. Tears in eyes tell the others that you are sad. When you put up your hand in class, the teacher knows you want say something. Other things should also carry messages. For example, a sign at the bus stop helps you to know which bus to carry. Signs on the door tell you if to go in or out. Have you ever seen that there are a lot of sign around you and that you receive messages from it all the time?

螺旋分级机的螺旋主要由（）、支架螺旋叶片和衬铁组成。