凡妊娠12周内，胚胎自然殒堕者，称为( )
A．小产B．胎动不安C．胎漏D．滑胎E．堕胎
参考答案：E
高等植物中淀粉磷酸化酶即可催化α-1，4糖苷键的形成，也可催化α-1，4糖苷键的分解。
As countries ______ to increase yields on existing croplands through intensified use of water, energy, and fertilizers, the cost of commodities will rise.
A．encounter B．enchant C．enlarge D．endeavor
