________ these experiments were successfully completed would we think of going into humans.
| A．If only | B．Only if | C．So that | D．Even if |
Heads from different countries gathered in Amsterdam and President Xi jinping _____ a speech on nuclear safety.
| A．stated | B．issued | C．delivered | D．addressed |
Inner beautity takes _____ a casual glance to appreciate and it is much more importnat than physical beauty.
| A．more than | B．less than | C．other than | D．sooner than |
She _____ her mother in appearance but they are different from each other in character.
| A．resembles | B．looks | C．is similar | D．likes |
Scientists are increasely _____ that the earth is getting hotter because of carbon dioxide and other gases.
| A．content | B．conscious | C．convinced | D．common |
For the sake of enough time for study and rest, students are _____ from using cellphones in our school.
| A．encourged | B．forbidden | C．required | D．kept |