当四格表的周边合计不变时,如果某格子的实际频数有变化,则其理论频数()
A.不变
B.减小
C.增大
D.随该格子实际频数的增减而增减
E.不确定
参考答案:A
The stamps were __________ according to their styles and features.
A.found out
B.turned out
C.put out
D.sorted out
A fence was built to ______________ the garden. [ ]
A. guard
B. defend
C. protect
D. prevent