4. When you [
(a) will have finished
(c) will be finished
]reading the book, please put it back where you found it.
5. "Is Bill still using your car?"
"Yes, I don't know when he [
(a) has returned
6. Until the snow [
(a) has stopped
(b) returned
(b) have finished
(d) have been finished
] it."
(c) returns
], the train will not be able to move.
(b) stopsol dum (c) will stop
elect
(d) will return
ow (d) will have stopped