如图所示，为一物体做匀变速直线运动的速度图象，根据图线做出以下几个判定，正确的是（   ）

某工厂计划两年把产品的成本下降19%，则平均每年下降（　　）

    I have a new schoolbag. It is beautiful. It is yellow and blue. I like it vey much. But my schoolbag is very heavy. There are many things in my schoolbag. Look, what's in it?

    I have two books, a notebook, four pencils, two crayons, a ruler, and an apple in my schoolbag.

根据课文内容回答问题，将问题的答案填写在横线上。

随着社会主义新农村建设的开展，农村的厨灶发生了革命性的变化．原来的煤球炉已经被液化气灶代替．液化气与煤相比，热学方面突出的优点是热值 ____；液化气瓶中的实际上装的是液体，它是用 ____的方法使气体液化．若用液化气灶将质量为5kg的20℃的水在标准大气压下烧开，水所吸收的热量是　 ____　J．c_水=4.2×10³J/（kg•℃）．

=____， =____