---Alice, why didn’t you come yesterday?
--- I______, but I had an unexpected visitor.
| A．had | B．would | C．was going to | D．did |
.I just wonder _____ that makes him so excited.
| A．why it is | B．what it is | C．why is it | D．what is it |
Thanks to your help, ________ I would not have completed the task on time.
| A．however | B．because | C．so | D．otherwise |
The conflict had developed into a stage ______ the two countries were gathering big troops on the border.
| A．where | B．when | C．which | D．that |
The schools themselves admit that not all children will be successful in the jobs ______ they are being trained.
| A．in that | B．for that | C．in which | D．for which |
______ scientists know where a storm will happen, winds will suddenly change, carrying the storm to a new direction.
| A．Even if | B．Since | C．Despite | D．Unless |