①下列做法会加剧温室效应的是____(填字母).
a.植树造林 b.燃煤供暖 c.风力发电
②下列防治“白色污染”的正确方法是____(填字母).
a.使用可降解塑料 b.露天焚烧废弃塑料 c.直接填埋废弃塑料
③为减轻大气污染,多个城市已禁止燃放烟花爆竹.“禁止燃放烟花爆竹”的标识是____(填字母).
Rick and Mary are from America.Now they are working in Tianjin.They can speak a little Chinese.Every morning they get up very early.Then they go to work by car.·They are very busy.They have lunch at the factory.①After lunch they work again.They finish their work very late. In the evening they take Chinese lessons(上汉语课).They want to talk with Chinese people.They often say,“Chinese people are very friendly(友好的).”②They like to stay in China and they like to work with Chinese people.
根据短文内容,完成下列题目。
据商务部网站消息,2016年一季度,全国实际使用外资金额1 418.8亿元人民币(折225.2亿美元),同比增长2.7%。双向投资呈现良好发展态势。这反映出我国( )
①开放型经济水平不断提高
②着力培育开放型经济发展新优势
③进入了对外开放的新阶段
④坚持“引进来”和“走出去”的更好结合
下列命题:①菱形的四个顶点在同一个圆上;②正多边形都是中心对称图形;③三角形的外心到三个顶点的距离相等;④若圆心到直线上一点的距离恰好等于圆的半径,则该直线是圆的切线。其中是真命题的有( )