You look so tired. Why ____________ to have a rest ?
We should be strict _____ ourselves ____ our work.
The number of the children in the school ________ about three hundred. ________ of them________ from the countryside.
China has a history of more than five ________ years.
The girl ________ by the lake yesterday.
– I hear Yang Yan made an English speech at the graduation ceremony yesterday.- ______, and _______.