A:∠AOF和∠DOE
B:∠EOF和∠BOE
C:∠COF和∠BOD
D:∠BOC和∠AOD
选项
物 质
操 作 方 法
A
Cu( Fe )
加入过量稀盐酸,充分反应后过滤
B
NaOH溶液 Ca(OH)2 溶液
加适量的碳酸钠溶液,充分搅拌后过滤
C
NaCl溶液( Na2 SO4溶液)
加入适量的氯化钡溶液,充分反应后过滤
D
CO2( HCl )
通入足量的氢氧化钠溶液,干燥
例:—How many pencils do you need?
—I need four pencils.
—How much are they? two dollars for one
—They are eight dollars.