33.Only after he had spent several nights working on the math problem_______to wonder whether the problem was wrongly set.
Children need friends ______ their own age to play with.
We do not think the twelfth fiveyear plan for our city is practical ________ recent developments.
The invention of artificial hearts marked a turning point in the battle ________ heart disease.
This urban special school always accepts hearingimpaired students, ________ their educational level and background.
She's got the job because she has the advantage ________ others of knowing many languages.