Genetically modified seeds __________________ in the U.S. since 1996 A: have been grown B: has been grown C: have grown D: has grown

In ten year’s time, all those youngsters will become grown-ups.

Six years ago lots of tea plants_______________ on the hill. A: is grown B: grown C: grew D: were grown

The population of the world______still________. A: has;grown B: will;grow C: is;growing D: is;grown

What is the main idea of the text A: organically grown foods are nutritious. B: how to buy organically grown foods. C: what does organically grown foods mean D: a general standard should be established to regulate the organically grown produce.

Belgian blue bull: ( ) A: It is a bull grown lots of muscle because a gene is inhibited. B: It is a bull grown lots of muscle because a gene is overexpressed. C: It is a bull grown lots of muscle because a gene that is missing. D: It is a bull grown lots of muscle because a gene that is duplicated.

UPS线上发货服务有（ ）。 A: UPS Express Saver B: UPS Expedited C: UPS Express D: UPS Saver

大多数（）的切换时间为4MS-8MS A: 后备式UPS电源 B: 在线式UPS C: UPS D: 后备式UPS电源，在线式UPS，UPS都不对

如果按效率的高低来排序，则以下排列正确的是（） A: 双变换在线式UPS＞在线互动式UPS＞后备式UPS B: 在线互动式UPS＞双变换在线式UPS＞后备式UPS C: 后备式UPS＞在线互动式UPS＞双变换在线式UPS D: 后备式UPS＞双变换在线式UPS＞在线互动式UPS

隔离冗余UPS系统中有一个或多个单机UPS系统作为主UPS，一个单机UPS系统作为备用的UPS（或称为冗余UPS）。每个主UPS都为其输出母线上的负载供电，备用UPS作为主要UPS的（）