249. 麦饼比米饼便宜。
[误] A cake made of wheat costs less than that made of rice.
[正] A cake made of wheat costs less than one made of rice.
注:that 是从 the 变来的,属于定冠词的范围之内,所以它只能代表有定冠词的单数名词,如 The cost of oil is less than that of gas. 但凡是有不定冠词的单数名词,就不能用 that 代表,只能用 one 代表,如上举的两个例句:one=a cake,而 that=the cost。对于有定冠词的单数名词,也并不一定非用 that 代表不可,如 The step you have taken is that of much risk. 一句中的 that 就错了,应改为 one 才对,因为在动词 is 后应接 a step,所以只能用 one 代表。