问题
单项选择题
Attempts have been made for nearly three decades to increase the amount of precipitation from clouds by seeding them with salt or silver iodide.
A．Devices
B．Hypotheses
C．Efforts
D．Suggestions
答案
参考答案：C
解析： 名词辨析。 attempt努力，尝试：abandon the attempts放弃尝试。device装置：a device for opening bottles一个打开瓶子的装置。hypothesis假设：This is only a sort of scientific hypothesis which has not been proved by experiments．这仅仅是一个尚未被实验证明的科学假说。efforts努力，尽力：Please put more efforts into your school work．请你在功课上再努点力。
