2.a.1.Because I'm sick.2.No, I'm sorry, I'm busy tonight.3.Because it is exclusively for teachers.4.It is quite difficult because I have to deal with many angry customers.5.I like communicating with our partners.b.1.fara on2.missing for five days3.I've found my4.the house had been burgled5.I didn't get along very wellc.1.went off2.me he had been working3.not to do it4.promised to buy her 5.if smoking was allowed