--- AIR IS ONE OF THE MANY PROBLEMS WE HAVE TO SOLVEA PURE B POLLUT...

39. - TRAC NGHIEM ANH 9 HKII 2
TRAC NGHIEM ANH 9 HKII 2

39.--- air is one of the many problems we have to solve

A Pure

B Polluted

C Dust

D Pleasant

:40 We couldn't go on a picnic as planted --- it was raining hard

A however B but

C because

D so