According to the author, climate researchers ______.

A．are quite sure about why it's getting hotter and hotter

B．declared that we humans are the cause why it's getting hotter

C．have discussed the possible causes why it's hotter

D．have claimed that changes in nature are the roots of hot days

恒牙易发生龋齿的部位如下，除外

A．咬合面点隙和裂沟

B．牙齿邻面和牙颈部

C．扭转和重叠的牙面

D．不易被清洁的牙面

E．牙尖和切缘