抽油机外抱式刹车装置制动力（）。A、最大达174kN B、最小达174kN C、最大达1

已知i=（1，0），j=（0，1）则i-2j与2i+j的夹角为．90°

1999年WHO/ISH高血压诊断标准是（mmHg） （）

A.收缩压>130和（或）舒张压>85

B.收缩压>140和（或）舒张压>90

C.收缩压≥140和（或）舒张压≥90

D.收缩压>160和（或）舒张压>100

E.收缩压≥160和（或）舒张压≥100

假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。错误涉及一个单词的增加、删除或修改。 

增加：在缺词处加一个漏子符号（/\），并在其下面写出该加的词。 

删除：把多余的词用斜线（\）划掉。 

修改：在错的词下划一横线，并在该词下面写出修改后的词。 

注意：1. 每处错误仅限1词； 

2. 只允许修改10处，多者（从第11处起）不计分。 

When I was in high school, most of my friend had bicycles. I hoped I could also have it. One  

day I saw a second-hand bicycle, that was only one hundred yuan. I asked my father /\ the money.   But he said he could only give me half of the money. He should find the other half myself. So I went to sell newspapers after the school. My father was pleased if I showed him the money a month after. He gives me the other fifty. You can imagine how much happy I was when I rode to school on later gave my own bicycle.

工程项目管理是以( )为核心的管理活动。

A．项目经理

B．一定的组织形式

C．工程项目目标控制

D．实现投资效益