【单选题】The old lady watched her grandson ____ a yo-yo yesterday afternoon.
【单选题】氯化消毒是我国目前饮用水消毒最常用的方式,供饮用水消毒的氯制剂主要有液氯、漂白粉、漂白粉精和有机氯制剂等,氯化消毒过程中起主要作用的物质是
【单选题】The passage indicates that Alzheimer's is a disease ______.
A.
common to people, old and young
B.
not costly to be cured
D.
not easy to be diagnosed
【单选题】How old _______you? I _______ten.