An alloy is a combination of two or more different metals.

　　合金是兩種以上不同金屬結合而成的。

　　A combination of internal and external factors caused the company to close down.

　　內外因結合導致了公司的倒閉。

　　The two players together make a formidable combination.

　　這兩個隊員配對兒，難以對付。

　　She brings to the job a rare combination of youth and experience.

　　她很年輕，然而干這份工作已有經驗，這是很難得的。

　　This combination of qualities is generally supposed to be extremely rare.

　　一般認為，同時具有這樣一些品質極為罕見。