87.You__(本来不必进行)all those calculations.We have a computer to do that sort of thing.
88.__(中国居于方便面需求榜首)，followed by Indonesia，Japan and the US.
89.Some，green.h0.u，se gases occur naturally in the atmosphere，while others____ __ (由人类的活动造成).
90.Maintaining proper weight is__(可以采取的最好的步骤之一)to prevent many health conditions and diseases.
91.Hardly had he finished his work____(电话就响了).
