— My eyesight is getting worse these days. I'd like to have my eyes ______.
— Perhaps you should consider ______ the time on the computer.
A:checked; to reduce
B:to check; reducing
C:checked; reducing
D:checking; to check
下列说法中,正确的是()
下列的各点中符合东半球、北半球、低纬度三个条件的有( )
萃取法是将粉碎、干燥的植物原料用有机溶剂浸泡,使芳香油溶解在有机溶剂中,蒸发出某种物质后,就可以得到纯净的植物芳香油。蒸发出的物质是( )