众所周知，词汇是
be tied to 与……紧密相关
释义
If one thing is tied to another or two things are tied, the two things have a close connection or link.
例句
Toxicological evidence suggests that certain cancers are clearly tied to exposure to air pollution.
GRE
Fertilizer prices, largely tied to the price of natural gas, huge amounts of which go into the manufacture of fertilizer, will continue to represent an enormous and escalating economic burden on modern agriculture, spurring the search for alternatives to synthetic fertilizers.
化肥的价格与制造化肥所需要的天然气的价格密切相关，进而会变成现代农业所需要承担的越来越重的经济负担，这促使人们寻求合成化肥的其他途径。
(编辑：Sally)