To their great relief, the missing child returned home, ______, after an absence of two weeks.
| A．looked tired and healthy | B．tired and healthy |
| C．tiredly and healthily | D．looking tired and healthily |
___ that may generally reduce the amount of labor needed on construction sites by 90 percent.
| A．So clever the construction robots |
| B．Such construction robots are clever |
| C．So clever are the construction robots |
| D．Such clever construction robots are |
___ most of the earth’s surface is covered by water, fresh water is very rare and precious.
| A．As | B．Although | C．If | D．Once |
Helen was much kinder to her youngest son than to the others, ______, of course, made the others envy him.
| A．who | B．which | C．what | D．that |
_____to reach them on the phone, we sent an email instead.
| A．Fail | B．Failed | C．To fail | D．Having failed |
He let me repeat his instructions_____ sure that I understood what was _____ after he went away.
| A．to make; to be done | B．making; doing | C．to make; to do | D．making; to do |