—He, together with Tom, _____ going to visit Shanghai in July. How about you?
—I'm afraid I have to stay at home _______
A：are; on my own
B：is; by my own
C：are; on myself
D：is; by myself
北半球夏季长于冬季是由于（ ）
一人利用左右两手水平向两端拉一支弹簧秤，若两手所施的拉力都是20N，则弹簧秤的示数为（ ）
“远征号”潜艇从长江某基地赴东海执行任务过程中(ρ海水＞ρ水)( )
护士在给患者输液时，常用橡皮软管扎紧患者的前臂．这时会发现患者手背上有“青筋”突起．这些“青筋”是（ ）
