New words：
challenge [ˈtʃæləndʒ]
n.挑战；质疑
v.向(某人)挑战；考查；盘问；对…怀疑（或质疑）
Sample Sentences：
He raised a challenge to the decision.
This math problem is a challenge for most students.
The teacher gave us a challenge to read 10 books this month.
Tom challenged me to a race after school.
The police challenged his ID at the airport.
Their school challenged ours to a football match.
I don't have the courage to challenge my boss's decision
New words：
record /ˈrekɔːd/ n.记录；唱片；记载；经历
Sample Sentences：
She loves listening to jazz records.
The police checked his criminal record`.
His sports record includes many awards.
She broke the world record in swimming.
The school has a record of all students’ grades.
New words：
record /rɪˈkɔːd/ v.记录；录制；记载；录（音）；（仪器）显示，标明
Sample Sentences：
The thermometer recorded 38°C.
The device records the speed of the car.
She recorded her daily thoughts in a diary.
I want to record my favorite radio program.
They recorded a video message for their grandma.
The teacher asked us to record the experiment steps.
record /ˈrekɔːd/ n.记录；唱片；记载；经历
New words：
millimetre [ˈmɪlɪˌmitər] n.毫米；千分之一米millimeter [ˈmɪlɪˌmitər] n.毫米；千分之一米
Sample Sentences：
One centimetre equals ten millimetres.
These jellyfish were only one millimetre long.
Brisbane recorded 790 millimetres of rain in a week.
The land moves northwest by four millimetres per year.
New words：
centimetre [ˈsentɪˌmitər] n. 厘米
centimeter [ˈsentɪˌmitər] n. 厘米
Sample Sentences：
There are 2.54 centimetres to an inch.
One hundred centimeters make one meter.
One centimeter is equal to 10 millimetres.
Mr Zebra is 10 centimetres taller than Mr Deer.
millimetre [ˈmɪlɪˌmitər] n.毫米；千分之一米millimeter [ˈmɪlɪˌmitər] n.毫米；千分之一米