5. This is the four-stroke cycle which is in common use. An alternative cycle is the two-stroke cycle, which combines the exhaust and compression strokes into one.

这就是常用的四冲程循环。另一种循环是两冲程循环，它把排气冲程与压缩冲程合并为一个冲程。

6.We had to fight:there was no(other)alternative.

我们只有战斗，别无其他办法。

四、表示一个办法外的另几个或几个办法以外的另一个或几个如果只有一个alternative,则前面用an,有两个以上alternative, 则前面用零位冠词,数词,many,a number of,other等。alternative后可以接to引出名词或动名词表示原有的办法（或方案等）。例如：

7. Computers are very expensive so that unless the firm is fairly large and can use one almost full-time it is uneconomic to rent or buy it. There is an alternative which many small firms take. They buy microprocessors.

计算机价格昂贵，因此，除非公司相当大又几乎能在全部办公时间内利用计算机，那无论是租用还是购置计算机都是不合算的。很多小公司采用一种变通的办法，就是购置微处理机。

8. If a particular item asked for is out of stock, the computer may suggest alternative items which might satisfy the customer. 

如果顾客要买的某种商品缺货，计算机可以推荐一些也许会使顾客满意的代用品。

9. Many alternatives to oil and gas are already in use, at least in a small way.

石油和天然气的代用品已有多种投人使用，至少已小规模地使用。

责任编辑：admin