It's less time-consuming and more convenient to send an email than to write a letter.
time-consuming
adj.
耗时的
用it 做形式主语,结构上更地道. 而并非那种直译,一一对应.
less time-consuming 和more convenient, 以及to send an email和 to write a letter都保持了结构上的对称.读来更顺口.
也许这样翻译很正式 但没问题
提问者对于答案的评价:very earnest ! cool ! and thannks :0