—Sure. Next month.
A:when you will travel
B:when you travelled
C:when will you travel
D:when did you travel
人固有一死,____,____。(司马迁《史记》)
A. Nice to meet you, too
B. My name is Sarah.
C. Thank you.
D. Hi, I'm Amy.
利用等重滑轮,分别采用如图所示的两种方式提升同一重物,升高相等高度.若绳重和摩擦不计,下列分析中正确是()