it is 要不要改为they are：要,要一致.
saving time 要不要改为 time-saving?：要,形容词 time-saving指节约时间的,与前面形容词convenient一致请问这里的they 是否是指代advantges.那这样可以把that they are 去掉吗？你很仔细啊。对的，这样更好！我觉得去掉that they are 好像不太合适，因为去掉翻译出来就是“电脑优点是方便的和省时的”有点逻辑上的问题，若不去掉就是“电脑的优点在于它是方便的和省时的”这样如何?the advantages of the computer are that it is convenient and time-saving. （it指computer）或the advantages of the computer are convenient and time-saving.