New words：
serpent [ˈsɜrpənt] n. 蛇；（尤指）大蛇
cast [kɑ:st] v. 蜕(皮)；脱(壳)；脱落
Sample Sentences：
Serpents cast their skin once a year.
I killed a serpent but my fear's always there.
The peach trees cast all their blossoms after the heavy rain.
blossom ['blɔsəm] n.花朵
New words：
period ['piəriəd] n. 时期；阶段；周期；课时
Sample Sentences：
Which period of history are you studying?
We have three periods of chemistry a week.
This was the most difficult period of his life.
He was on his feet again after such a long period in hospital.
New words：
cough [kɔf]
n.咳嗽；咳嗽声；咳嗽病
v.咳嗽；（从喉咙或肺中）咳出
Sample Sentences：
The old lady had a bad cough.
The doctor has given me some medicine to take for my cough.
Cover your mouth when you cough.
She coughed blood again this morning.
New words：
jaw [dʒɔ:] n. 下巴；颌；下颌
panther ['pænθə] n. 黑豹；美洲豹
Sample Sentences：
The panther held a snake in its jaws.
My jaw dropped when I saw how much the meal had cost.
He has seventeen teeth in the upper jaw, and nineteen in the lower jaw.
New words：
bare [ber] adj.裸体的；裸露的；（树木）光秃秃的；（土地）荒芜的
Sample Sentences：
The dog bared its teeth.
The trees are bare in the winter.
The child was bare to the waist.
The walls were bare except for a clock.
Avoid touching food with your bare hands.