在△ABC中，∠C=90 °，a，b，c分别是∠A，∠B，∠C的对边，下列等式：

洗胃时每次注入的洗胃液的量常为（）。

A.100～150ml

B.200～250ml

C.300～500ml

D.500～600ml

E.700～800ml

已知△ABC是等腰三角形，则（　　）

A．AB=AC

B．AB=BC

C．AB=AC或AB=BC

D．AB=AC或AB=BC或AC=BC

_________is known to us all is that the old writer, for __________ life was hard in the past, still works very hard in his eighties.

A．What; whom

B．As; whom

C．It; whose

D．What; whose

Multipurpose Internet Mail Extension (MIME) is a (2) document messaging standard in the Internet enviroment, with MIME, users can send (3) Email messages that include audio, video, graph-ices, and text to any other user of a TCP/IP network. Richtext information can also be (4) into messages. It defines the fonts, formats, and (5) features of a document so the document can be easily (6) on many different types of systems.

A) analogB) many C) multmediaD) digital

在交谈中，态度要谦恭，语言要文明，另外还要注意避免出现哪10种情况？