A:should be; be operated on
B:were; must be operated on
C:be; was operated on
D:was; be operated on
下列地区中,人口分布较为稀疏的是( )
保护环境 从我做起
98,94,90,86,____,____,____,____,____。
下面关于力的说法中,正确的是( )