Michael promised he ________ my e-mail as soon as he went back home.

He says he knows everything about DIY. ________， I know much more than he does.

ts made from apples, such as pies, applepancakes and apples _____ in sugar are available for sampling

Qian Xuesen tried many times _________ he found thesolution to the puzzle about space technology

To understand the complex situation completelyrequires more thought than ________ so far.