A:开发太阳能等新能源汽车
B:工业污水直接用于灌溉农田
C:焚烧废旧塑料防止“白色污染”
D:推广露天烧烤丰富人们饮食
They ________ carefully, but they didn't ________ anything.
如图所示,在托盘里放重物,使木块A的木质面与木板表面接触,当木块质量为300g时,木块在木板上匀速运动,托盘里重物质量为60g,求:
—You just have ___________. Wait until you finish this competition.
河北省大力发展反季节蔬菜、花卉、草皮、中高档水果的主要原因是( )