3. Mark the correct alternative: 3.1. They good friends, but my sister a) is / are b) isn't / is c) are / isn't d) are / are 3.2. Hello! we all here today? No, someone missing. a) are / am b) is / am c) are / are d) are / is 3.3. Is Henry tired? Yes, a) he is b) Henry is c) he is not d) he's​