science and technology

有时两个名词虽由and连接,但习惯上被看作是一样东西,这时动词也用单数：
Bread and butter is enough for me．
Whisky and soda is his favourite．
Duck and peas is delicious,but eggs and bacon is better．
That cup and saucer is broken．
The wheel and axle is out of repair．
A needle and thread is all my grandmother needs．
Romeo and Juliet is a tragedy．