they don't die because of the tumour.通常不会死于这种肿瘤

because of:因为； 由于

The game was cancelled because of the rain.

比赛因为下雨而取消了。

Scientists knew that the hypothalamus was involved in switching the appetite on and off.科学家知道下丘脑与调控食欲有关

involve in:卷入； 陷入

I got involved in a quarrel about the price.

我被卷入了一场有关价格的争吵。

switch on:(用开关)开启

The video is programmed to switch on at ten o'clock.

电视机设定在10点钟自动打开。

switch off:(用开关)关掉

Do you mind if I switch the radio off?

我可以关掉收音机吗？

Researchers spent ten years comparing this mutant mouse with other thin mice.科学家花了十年的时间来将这只基因突变的老鼠和其它瘦老鼠对比

compare with:与 ... 相比

Compare with those who is suffering, we are better off.

跟那些受苦的人相比，我们过得很好了。

How does your bike compare with mine?

你的自行车怎么能和我的自行车相比呢?