1.The police suspect there may be a ___________ (联系) between the two cases.
2.We're faced with a s___________(严重的) situation where we have to give up what we're eager for most.
3.There was no p___________(证据) that the knife belonged to her.
4.In a world that warms up by 3℃, it found that m___________(许多的) changes to the colour of the oceans would occur.
5.This switch has d___________(减少) pollution in the country's major lakes and reservoirs and made drinking water safer for people
