设X在区间[a,b]上服从均匀分布,则数学期望EX=()
A.a+b
B.a-b
C.(a+b)的2倍
D.(a+b)的一半
参考答案:D
Read and judge. 请你根据短文内容判断正(T)误(F)。
It's summer. Zoom and Zip swim in the lake. They are happy. "I like summer," says Zip. "Why do you like
summer?" asks Zoom. " Because I can swim in the lake."
It's fall. Zoom and Zip go hiking. They eat a lot.
Winter comes. Zoom and Zip don't skate. They sleep.
Spring comes. Zoom and Zip wake up. They fly kites. "I like winter," says Zoom. "Why do you like
winter?" asks Zip. "Because I can sleep a long time."
( ) 1. In fall, Zoom and Zip eat a lot.
( ) 2. Zip doesn't like summer.
( ) 3. Zip and Zoom can sleep a long time in fall.
( ) 4. In summer, Zip likes swimming.
因公致残是指在()中致残,经医疗终结,符合评残条件的。
A.对敌作战中
B.执行公务中
C.服役期间
D.执行军事演习