They would leave subtle clues in the isotopic composition of the limestone by shifting the ratios of light to heavy carbon and oxygen atoms in its calcium carbonate.
Traffic conditions refer primarily to the composition of the traffic stream, particularly the presence of trucks and other heavy vehicles.
交通条件主要指的交通流，特别是卡车和其他重型车辆的存在组成。
3
The fundamental method, program composition, actual application of the research of simulation on heavy haul trains and various specific simulation researches are described.