The poor man, __________, ran out of the dark cave.
| A．tiring and frightened | B．tired and frightened |
| C．tired and frightening | D．tiring and frightening |
Bears ______ fat stores throughout the summer and fall to have energy enough to last them through their winter sleep.
| A．pack up | B．build up | C．bring up | D．take up |
With many cities in China dreadfully blanketed by thick haze, the environmental problem is _____ Chinese people concern most nowadays.
| A．what | B．which | C．where | D．when |
According to scientists, our mental abilities begin to _____ from the age of 27 after reaching the highest level at 22.
| A．differ | B．shrink | C．fail | D．decline |
Smiles around the world _____ be false, _______ other feelings like anger, fear or worry.
| A．must; hide | B．shall; hiding |
| C．may; hide | D．can; hiding |
The doctor tried to laugh my brother _____ his fears about the coming operation.
| A．from | B．against | C．off | D．Into |