以下哪项不是食品中天然有毒有害成分？（）
A.四季豆中皂苷
B.杏仁中氰苷
C.鱼中组胺
D.河豚毒素
E.有毒蜂蜜
参考答案：C
——Do you have any idea when the project will be carried out?
—No, but I have heard that it was not until last month _______ it was approved.
A．that
B．when
C．since
D．before
外表表面缺陷深度超过管子规定厚度的（）以上时，应提交业主和制造厂研究处理及签证。
A.10%
B.15%
C.20%
D.8%
