【简答题】In contrast to inorganic compounds, the molecular attraction of organic compounds is weak, so organic compounds are usually volatile and possess low melting points.
【单选题】What the plants pump through the air is a mixture of chemicals known as volatile organic compounds, VOCs _____ _______.
【多选题】分层选样法的优点包括:
C.
将相对同质的项目划为一类,可提高样本在其所在层次的代表性
D.
对于项目之间特征差异较大的总体的样本选择更具优越性
【多选题】与次等劳动力市场相比,优等劳动力市场的特征包括( )。
【简答题】In contrast to inorganic compounds, the molecular attraction of organic compounds is weak, so organic compounds are usually volatile and possess low melting points.
【单选题】下列选项中,对细菌杀虫剂-苏云金芽孢杆菌描述不正确的是:()。
A.
该菌对鳞翅目、双翅目、膜翅目、鞘翅目、直翅目和毛翅目等多种昆虫有不同程度的致病性
C.
内毒素是最主要的杀虫毒素,它伴随着芽孢的形成而产生