1.、in the light of recent discoveries it may be necessary to

題目：

1.、in the light of recent discoveries it may be necessary to revise our previous theory.
爲什麼用in the light of ,不用in line with
2.washing the food down with water a substitute for chewing is not a good habit.
3.i asked him to spare me a few minutes so that we could go over all the problems.
4.this type of desk and chair can be adjusted to the height of studentsat different ages.
5.a formal is preferable to a casual one for such an occasion .爲什麼用preferable,不用不用suitable.

解答：

2.washing the food down with water a substitute for chewing is not a good habit.
答：這題有問題.原題句應爲：
Washing the food down with water as a substitute for chewing is not a good habit.
譯：靠水將食物衝下來代替咀嚼,這不是一個好習慣.
as a substitue 作爲一種替代的方法.