Tom is reading a book _______ his brother is watching TV. [ ]

A. while

B. though

C. however

D. but

烧伤休克的特点

A．有效循环量减少逐渐发生

B．血液有形成分大量破坏

C．有效循环量迅速减少

D．快速补液可迅速纠正

E．血液中电解质变化不明显