6complete the sentences with must, might or can't. 1 this ring be gold -it only costs £1.99! 2 lt be my book- it's got my name in it. 3 david isn't at school today. he be ill, but perhaps he's on holiday 4 alison's got lots of cats. she like them. 5 they be from yakutia, but i'm not sure. 6 he be scared of heights - he went climbing in the pyrenees last year.