【单选题】单元体的应力状态如图示,其主应力有何特点 ?
B.
σ 1 =0 , σ 2 =σ 3 <0< /div>
C.
σ 1 >0, σ 2 =0, σ 3 <0 ,∣ σ 1 ∣=∣ σ 3 ∣
D.
σ 1 >0, σ 2 =0, σ 3 <0 ,∣ σ 1 ∣> ∣ σ 3 ∣
【简答题】In what aspect did the statistics show of aging Americans?22:In what aspect did the statistics show of aging Americans?
【简答题】What did several countries take part in 18?22:What did several countries take part in 18?
【简答题】在下面案例中,教师采取了什么方法组织教学?教师在运用此方法时注意了哪些问题?存在哪些不足? 案例: 一个幼儿抱着大皮球神秘地告诉老师:“老师,皮球还能拍呢” 。“你知道皮球为什么能拍吗?”教师反问她,她一本正经地说:“因为它里面有弹簧。”边说边用两手按了按球。老师问:“你怎么知道有弹簧呀?”她认真地说:“我们家气筒上面有一个小弹簧,妈妈把小弹簧一打,就打进去了。皮球就能弹起来了。”原来,在气筒上有...
【简答题】根据下列材料请回答 22~25 题: 第 22 题 What is John Harrison's job? ( )
【单选题】__________unexpected advice they have given us!