lazy
a.
1. 懒散的,怠惰的
His teacher thought he was lazy.
他的老师认为他很懒。
2. 使人倦怠的;懒洋洋的
The weather was lazy.
这天气使人无精打采。
3. 缓慢的,慢吞吞的
A lazy stream winds through the meadow.
一条缓慢流动的溪水蜿蜒曲折流经草地。

must1
v.aux.
1. (表示必要、命令或强制)必须,得
You mustn't talk like that.
你可不能这样说话。
You must do as you are told.
你必须遵嘱行事。
We must be home by six.
我们必须在六点以前回家。
2. (表示肯定的推测)一定是,谅必,八成
This must be your room.
这一定是你的房间了。
He must be eighty now.
他现在八成有八十岁了。
3. (表示不可避免性)必然要,必定会
All men must die.
人总有一死。
4. (表示主张)一定要,坚持要
If you must go, at least wait till the rain stops.
如果你坚持要走,至少也要等雨停了再走。
5. (表示与说话人愿望相反)偏要
The machine must break down at this busy hour.
正忙的时候机器偏偏坏了。
n.[S]
1. 必须做的事;不可少的事物
A walking stick is a must for me now.
如今我行走离不开手杖了。
2. 一定要看(或听、读)的东西
a.
1. 绝对必要的,必须的[B]
must2
n.
1. 葡萄汁,果汁[U]
must3
n.
1. 霉;发霉[U]

course
n.
1. 路线;方向[C]
Our course was straight to the south.
我们的方向是一直向南。
2. 过程;进程[U]
It was one of those ideas that change the course of history.
这便是那些能改变历史演进的观点之一。
3. 习惯的程序[C]
4. 方针,做法[C]
I think the only sensible course is to retreat.
我认为唯一明智之举是撤退。
5. (竞赛的)跑道;场地[C]
6. 课程,科目[C][(+in/on)]
She took a course in philosophy.
她选读了一门哲学课程。
7. 系列,连续[C]
8. 一道菜[C]
The first course was soup.
头道菜是汤。
9. 【建】层;一层砖石[C]
vt.
1. (用猎犬)追猎;追逐
2. 使(马等)奔跑
vi.
1. (液体)流动[Q]
Tears coursed down her face.
她泪流满面。
2. (用猎犬)追猎

lazy是懒惰的意思 

must必须的意思 


course 是课程的意思    of course 就是当然的意思