Areas where students have particular difficulty have been treated particular care.
Stephen Hawking believes that the earth is unlikely to be the only planet __________ life has developed gradually.
Children who are not active or __________ diet is high in fat will gain weight quickly.【选项 】
I refuse to accept the blame for something __________ was someone else's fault.
The old town has narrow streets and small houses __________ are built close to each other.
You'll find taxis waiting at the bus station __________ you can hire to reach your host family.