The ball curved through the air.

球在空中沿曲线运动。

The ball curved strangely in the air.

球在空中划出奇怪的弧线。

The ball looped high up in the air.

球高高飞起，在空中画了一条弧线。

In 'He grabbed the ball and threw it in the air', 'ball' is the antecedent of 'it'.

在He grabbed the ball and threw it in the air一句中，ball是it的先行词。

The ball is fully swelled with air.

这球已打足了气。