An alloy is a combination of two or more different metals.
合金是两种以上不同金属结合而成的`。
A combination of internal and external factors caused the company to close down.
内外因结合导致了公司的倒闭。
The two players together make a formidable combination.
这两个队员配对儿，难以对付。
She brings to the job a rare combination of youth and experience.
她很年轻，然而干这份工作已有经验，这是很难得的。
This combination of qualities is generally supposed to be extremely rare.
一般认为，同时具有这样一些品质极为罕见。