问0210语法啦!!!!!!!!!

kevin_2006UID: 2174251

11.______________over 100 years since the invention of the square-bottomed paper bag.
a)Now is
b)Now it has
c)There is now
d)It is now
问不是当遇到____+n.缺主谓的情况是优先选there be,不选it is 和they are(指代不清)吗?
为什么这题答案选d不选c?

28.Machines need energy (to function),(whether) it is animal or human muscle,wind or (waters) currents,or heat-generated energy ,(such as) steam.
                                                                             
不是说waters画线永远对吗?为什么c错????

xukai8273UID: 2165109

it 形式主语
waters --water   一致