中国医学史上首创方论的医学家是
A.王叔和
B.张仲景
C.成无己
D.吴鹤皋
E.汪昂
参考答案:C
根据短文内容及首字母提示,填写所缺单词。
My name is Nick. My family is big. We often have a good time at the w 1 . My mother c 2 for us, but she doesn’t w 3 the dishes. My father washes the dishes. He also c 4 his car. Sometimes, he goes fishing. My grandparents like w 5 TV very much. I don’t like watching TV at the weekend. I like c 6 with my friends on the Internet. My sister Lily l 7 listening to m 8 . She also likes watering the f 9 in the garden. We all e 10 our weekends.
在一条笔直的公路上有A、B两地,它们相距150千米,甲、乙两部巡警车分别从A、B两地同时出发,沿公路匀速相向而行,分别驶往B、A两地.甲、乙两车的速度分别为70千米/时、80千米/时,设行驶时间为x小时.
(1)从出发到两车相遇之前,两车的距离是多少千米?(结果用含x的代数式表示)
(2)已知两车都配有对讲机,每部对讲机在15千米之内(含15千米)时能够互相通话,求行驶过程中两部对讲机可以保持通话的时间最长是多少小时?