1) put "and, or, but, so" in the sentences:
a,
1 He likes english,____ he learns english best.
2 You should bring your umbrella,___ you will be wet.
3 Ann is very friendly,____ everyone likes her.
4 Jane is very rich,____ she is a good person.
5 The teacher doesn't come here,___ the students still study in class.
6 The environment is polluted,___ the weather is hotter and hotter.
7 He is fat,___ he is tall.