Manufacturers of the early 1900 s were using steel pipe, angle or channel for the greenhouse superstructures.二十世纪初期制造商们就已用钢管 、 角铁以及槽钢之类的材料建造温室的上部结构.Ships, Offshore and Marine Strutures : Above and below - water hull area...
The ripe wheat undulated in the Breeze like the incoming tide.成熟的小麦象潮水般随风起伏.The resulting waveforms depend upon the amplitudes, wavelengths, and timing of the incoming waves.形成的波的形式取决于到来的各波的振幅 、 波长和同步状况.The incoming powe...