He enrolled in an advanced calculus class, but he found it too difficult, so he dropped it.

The tidal wave ruined the crops, and it destroyed several villages, and it caused many deaths, so it was a real disaster.

The analysts worked many hours on the computer program, but they couldn't find the cause of the problem, so they finally gave up, and they went home.

Junk food is bad for your health, and it also contains no vitamins, and it damages your stomach, so people shouldn't eat it.

The lack of rainfall has caused a severe water shortage, so people have to conserve water every day, and they also have to think of new ways to reuse water, but the situation is improving.