γ射线的实质是（）。
A、氦核粒子流
B、高速离子流
C、电磁波
D、高速粒子流
参考答案：C
Do you see a little flag ___________ Australia's flag? [ ]
A. in
B. inside
The size of this house is much_____ than that one. [ ]
A. stronger
B. bigger
C. faster
D. cleaner
