电弧表面温度达()℃,弧中心温度可高达10000℃。
参考答案:4000~5000
Mr Brown and his family have _______ Sanya for a few weeks. [ ]
A. been in
B. worked
C. gone to
D. left for
以对症治疗为主的传染病是
A.细菌性痢疾
B.艾滋病
C.伤寒
D.病毒性肝炎
E.霍乱