买入和卖出股票的成本包括__________
A.经纪商佣金
B.买卖差价
C.投资者被迫做出的价格折让
D.A和B
E.AB和C
参考答案:E
There’s little important news in the newspaper today, ______?
A.isn’t there
B.is there
C.is it
D.are there
正常情况下,唾液中氟的浓度为()。
A.0.005mmol/L
B.0.01mmol/L
C.0.015mmol/L
D.0.02mmol/L
E.0.05mmol/L