其結(jié)構(gòu)是固定的，意思上的主語(yǔ)并不是句子的主語(yǔ)。
　generally speaking　一般說(shuō)來(lái)
　talking of (speaking of) 說(shuō)道
　strictly speaking 嚴(yán)格的說(shuō)
　judging from 從…判斷
　all things considered 從整體來(lái)看
　taking all things into consideration　全面看來(lái)

　　judging from his face, he must be ill.　從他的臉色看，他一定是病了。
　　generally speaking, dogs can run faster than pigs. 總的來(lái)說(shuō)，狗比豬跑得快。 (speaking 并不是dogs 的動(dòng)作)