泥沙水样实验室处理是（）测验的源误差之一。
A.细沙
B.粗沙
C.床沙
D.悬沙
参考答案：D
(2013·潍坊五校一模)—Have you been wasting time chatting online recently?
—________. I've been studying hard and I need a break.
A．Not really
B．Don't mention it
C．Not to worry
D．Never mind
为了改变货币供应量，中央银行通常采取开展公开市场业务和控制商业银行存款利率的办法。( )
