中国大学MOOC: He built a pair of wings of a size suitable to _______ his own weight, and made use of gravity as his motor.
举一反三
- He built a pair of wings of a size suitable to _______ his own weight, and made use of gravity as his motor. A: entertain B: retain C: obtain D: sustain
- 中国大学MOOC: In the past he often made his sister ____, but now he is often made _____ by his sister.
- 中国大学MOOC: He _____ his own health.
- He made it a ___ to bulid a successful business on his own in his district.
- He built up the business at the ______ (expensive) of his own health.