1．We should make a ____________(切实可行的) plan to stop pollution.
答案：practical
2．In the past, people used to use smoke to send __________(信号)．
答案：signals
3．They are fighting for rights and ____________(自由)．
答案：freedom
4．Put the meat in the ____________(冰箱)，or it may go bad easily.
答案：refrigerator
5．She works as a ____________(清洁工) and makes contributions to the environment.
答案：cleaner
