must　一定；肯定 (100%的可能性)

may\could\might　可能；也许（常用于肯定句中）

can't 　不可能；不会 (可能性几乎为零)

can 可能......吗 常用于疑问句中

Call students' attention to a chart.and encourage them to make sentences to practice the target language.

Whose ......is this? It must be...... It could/ might be ..... It can't be ......

Step 4、Guessing game

Show some pictures to practice the target language.

It might /could /must be **'s .

= It might /could /must belong to **.

It can't be **'s .

He/She might /could /must be a/an ......

He/She might /could /must be doing sth .

Step 5、Play a game

The teacher prepares a magic bag, ask the students some questions.Then collect some things from the students .Encourage them to guess what they are and whose they are . Students try to answer the questions using the target langue.

Step 6、Pairwork

Show two groups of pictures，a suit and a hair band. Students make up conversations with their partners and discuss about the real owners. This