Nick's children___their homework three hours ago.b) did a) made 2. We are____some research at the moment. a) making b) doing 3. I m afraid I've__

Nick's children___their homework three hours ago.b) did a) made 2. We are____some research at the moment. a) making b) doing 3. I m afraid I've____a mistake in the calculation a) made b) done 4. He is working on an interesting____on nano-technology b) research a) investigation 5, The___ for the detection of the killer will continue. a) investigation b) research