科学家正在仔细观察实验。

The scientist is carefully ___observing the experiment.

科学家们正在仔细观察细胞的分裂过程。

The scientists are carefully ___observing the process of cell division.

所有司机都必须遵守交通规则。

All drivers must ___observe the traffic rules.

我们家每年都会通过点蜡烛来守岁。

Our family lights candles every year when ___observing New Year's Eve.