請(qǐng)問(wèn)instructing him...在句子中干什么成分？為何不是用to instruct him?The editor at once sent the journalist a fax instructing him to find out the exact number of steps....

The editor at once sent the journalist a fax instructing him to find out the exact number of steps.

目前分詞 instructing...，是隨著狀語(yǔ)，也暗示肯定的目的性。表示在發(fā)傳真的同時(shí)，“指示”這個(gè)動(dòng)作也在發(fā)生，也就是說(shuō)，兩個(gè)動(dòng)作是同時(shí)發(fā)生的。大家了解，不定式表示以后，目的性非常強(qiáng)。本句若用不定式 toinstruct...，“為了指示...才發(fā)電報(bào)”，不符合句意。

目前分詞作隨著狀語(yǔ)，也總是帶有目的性。比如：

She waited impatiently, hoping he could come earlier.

她不耐煩地等待著，期望他能早點(diǎn)來(lái)。

The professor put a finger in his mouth, tasted it and smiled,looking rather pleased.

教授把一個(gè)手指放進(jìn)嘴里，嘗了嘗，笑了，看著非常高興。

The secretary worked late into night, preparing a report for the manager.

秘書為了給經(jīng)理籌備一個(gè)報(bào)告而工作到深夜。