三脚桩

已知函数f（x）在R上满足f（2-x）=2x²-7x+6，则曲线y=f（x）在（1，f（1））处的切线方程是（　　）

A．y=2x-1

B．y=x

C．y=3x-2

D．y=-2x+3

— John seems happy, even though his wife left him and he lost his job.

— I think he ____ to put on a brave face.[ ]

A. will try

B. has tried

C. tries

D. is trying

投资银行

某男，60岁，有左室前壁心肌梗死病史，超声复查发现左心室心尖部有一边界明确回声团块紧贴于室壁上，其最可能诊断为

A．心室血栓

B．心室黏液瘤

C．栓子移行至左心室

D．感染性心内膜炎

E．寄生虫疾病

两齿轮啮合运动，Z1＝30、Z2＝10，若ω1＝57rad／s，则ω2为（）rad／s。

A.171

B.10

C.38

D.5