无支护基坑施工时,垂直坑壁坑缘的护道应( )。
A.适当加深
B.适当加长
C.适当增宽
D.适当减窄
参考答案:C
I was told that by 1990 things were beginning to improve, _________ quickly enough.
A.even if not
B.even I didn’t improve
C.if not improved
D.if even to improve not
在一个布口袋里装有大小质地均相同的黑色、蓝色小球各1个、红色小球2个,如果闭上眼睛随机地从布袋中取出一个球,记下颜色,放回布袋搅匀,再闭上眼睛随机的再从布袋中取出一个球.求:
(1)连续两次恰好都取出红 * * 的概率;
(2)连续两次恰好取出一红、一黑的概率.(要有明确的解题过程)