两者都可表示“慢”，但slow通常只与少数动词(如 go, drive, pass, climb, run, walk 等)连用，且应置于其后；而slowly则用法较广，且可置于动词之前或之后，有时还可置于句首。如：

He walked slowly [slow] up the path. 他沿着那条小路慢慢地走着。

She slowly opened the door. 她慢慢地把门打开。

Slowly, things began to improve. 情况渐渐有了好转。

Negotiations were going slowly, and not well. 谈判进展缓慢，也不顺利。

It is a good habit to eat slowly. 吃东西慢一点是好习惯。

He walked slowly past the house. 他从屋旁慢慢走过。

The balloon rose up slowly into the air. 气球冉冉升入空中。

Then the audience dispersed slowly. 然后观众慢慢散去。

【注】在某些特殊句型(如感叹句等)中，slow也可放在主语之前。如：

How slow [slowly] the time passes! 时间过得真慢!

The slower you drive, the safer you are. 车开得越慢就越安全。