Guizhou Huangguoshu Waterfall．Thousands of visitors come to visit it every year．（ ）
| A． |
is in control of |
| B． |
is responsible for |
| C． |
is known for |
__________ the help of modern technology， scientists got a photo of a black hole．（ ）
A．AtB．InC．OnD．With
Will you stay here for dinner with us？
Sorry， I ____________． My mother is waiting for me at home．（ ）
A．mustn'tB．can'tC．needn'tD．couldn't
What do you think of working as a doctor？
It 's a good job to help people keep___________．（ ）
A．busyB．strictC．healthyD．generous
Betty has a beautiful _________． She wants to be a singer in the future．（ ）
A．voiceB．lookC．noiseD．sound
Oh． my God! I forgot to bring my pen here．
Don't worry． I have two． You can use __________．（ ）
A．IB．meC．myselfD．mine