根据汉语提示，结合句子意思，在横线上写出恰当的单词或词组。

1. Some people _______ (当作) the pets as their family members.

2. Next year the _______ (二十九) Olympic Games will be held in Beijing.

3. It is not easy for me to finish the work _______ (独自) in such a short time.

4. Thank you very much for sending me so many wonderful _______ (邮票).

5. Not many families can afford to send their children _______ (出国求学).

下列关于原子和原子核的说法正确的是

A．γ射线是原子由激发态向低能级跃迁时产生的

B．居里夫妇最先发现了天然放射现象

C．原子核中的质子靠核力来抗衡相互之问的库仑斥力而使核子紧紧地束缚在一起

D．结合能所对应的质量等于把原子核完全分解为核子后所有核子的总质量减去该原予核的质量