due to

due to
由于，因为
His successes were largely due to luck.
他的成功主要靠运气。
Accidents due to driving at high speed were very common that weekend.
在那个周末因高速驾驶造成的交通事故很多.
Her good health is chiefly due to proper diet and regular exercise.
她身体好,主要原因是饮食得当以及经常运动.
Her good grades are due to her hard work.
她的好成绩是靠勤奋学习获得的.
The delay is due to the shortage of hands.
事情耽搁下来是由于人手不足。
Some students quit school due to poverty.
一些学生因贫困而辍学。
The stove smokes, which is due to the pipe being stopped.
火炉冒烟了，那是由于烟道堵塞的缘故。

详解：

due to /owing to /because of /thanks to 这些词组均表示“由于”之意。
due to用于较庄重的书面语中，侧重“起因于”，在句中多作表语，有时作状语。
owing to可以和due to换用，但在句中多作状语，也可作表语。
because of着重某个结果的原因，在句中通常作状语。
thanks to突出一种感激之情，含“多亏”意味。

drop in<-->each other