I'm reliable ah 后面的ah是什么意思

该不是SCI，在web of science 官网查不到该期刊。属于正版免费的普通英文期刊 Journal of Pollution Effects & Control deals with the introduction of contaminants into the natural environment that causes adverse changes in the form of toxicity of environment, damage to ecosystem and aesthetics ...

History of computer development 5th century BC, Chinese invented the abacus. It is widely used in commercial trade, and this is the first calculation tool. It’s also considered the prototype of a computer. Until the 17th century, computing devices have a second important step forwar...