现在我们***

③1951年和平解放西藏

④1950年中国人民志愿军抗美援朝

读一读，回答下列问题。
    Betty is very happy because she moves to her new home today. Her new home is very big and nice. It has three bedrooms. The big one is for her parents. The small one is for her brother Paul and the middle one is for her. Betty likes pink，so her bedroom is a pink room. The walls are pink. The curtains(窗帘)are pink. The bed and wardrobe(衣柜)are pink, too. Every day, Betty does her homework in her bedroom. Betty's father likes the new home, too. He likes the study because it's quiet. He can read in it. Betty's mum likes the kitchen. It is big and clean. She can cook nice food for the family. Paul likes the new home because the living room is so big and he can play games with his friends there.

某物体做匀速直线运动，它在30s内通过的路程是150m，它的速度是 ____m/s，它15s内通过的路程是 ____m，它在第40s内的速度是 ____m/s。

某国2010年生产A商品10亿件，单位A商品的价值量为10元。如果2011年该国从事A商品生产的劳动者数量增加10%，社会劳动生产率提高20%，其他条件不变，则A商品的价值总量为（   ）

2015年“世界水日”和“中国水周”活动的宣传主题为“节约水资源，保障水安全”下列说法正确的是（  ）