To shoot a lion和 to shoot at a lion的涵义并不相同。前者是“射中(或射死)一头狮子”，shoot是及物动词，lion是它的宾语;后者是“对准一头狮子射击”，shoot是不及物动词，lion是介词at的宾语。
由此可见，to shoot用于表示射击行动已获得预期结果的场合; to shoot at仅表示对准目的物射击，与结果无关，是否命中或有否打死，不得而知。
试对比下列的例句：
The spy was shot through the heart.
该间谍被击穿心脏。
He shot himself yesterday.
昨日他吞枪自杀。
I shot at thd bird but it flew away.
我举枪向鸟射击，可是它飞走了。
She shot at that target but missed it.
她向靶射击，但没有命中。
与之类似的词语有：
hit—hit at
grab—grab at
to catch the ball—to catch at the ball
to snatch the book—to snatch at the book
to grasp the straw—to grasp at the straw
