Introduction and Reading（第一课时）
1. contract vi.& vt. (使….)收缩；使缩小；订合同；承包
Metals________ when cooled. 金属冷却时收缩。
n. 合同 __________/___________ a contract签一份合同 vi. contract_______sb (for sth )
He __________ (contract )with the company for _________(design) the library.
