1mbar等于多少千帕？请计算280mbar等于多少千帕？50千帕等于多少mbar？

患儿8岁，右下第一恒磨牙深龋洞，去尽腐质，近髓，无任何症状，处理首选（）

A.垫底充填

B.二次去腐

C.活髓切断

D.根管治疗

E.根尖诱导成形术

The long service of decades of the to-be-retired with the company was ______ a present each from the President.

A．confirmed by

B．recorded in

C．acknowledged with

D．appreciated for

GIF文件格式采用了（）压缩方式。

A．LZW

B．Huffman

C．RLE

D．DME

冠状动脉粥样硬化最好发的部位是

A．右主干

B．左主干

C．左旋支

D．前降支

E．右回旋支

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