精确到万位
精确到亿位
1742791000
____
2954708400
16834259000
199999999
配方甲:在MS培养基中加入细胞分裂素和生长素,质量浓度均为0.5mg/L;
配方乙:在MS培养基各成分用量减半,并添加生长素,质量浓度为0.lmg/L;
配方丙:在MS培养基中加入细胞分裂素和生长素,质量浓度分别为:2~3mg/L和0.02~0.3mg/L.
请回答下列问题:
如图,a∥b∥c,
(1)若AC=6cm,EC=4cm,BD=8cm,则线段DF的长度是多少厘米?
(2)若AE:EC=5:2,DB=5cm,则线段DF的长度是多少厘米?
句子配对。
①How heavy is Tom?____ A. There are 15.
②How old is he?____B. He is 15years old.
③How much is the robot?____C. He weighs 51kg.
④How many boys are there under the tree?____D. It's September 15th.
⑤When is your birthday?____E. It's ¥15.
对于做曲线运动的物体,下列说法正确的是( )