【判断题】部分预应力混凝土结构,施加荷载时结构的正截面出现拉应力,或者出现不超过规定裂缝宽度的裂缝。
【单选题】Suppose a country abandons a no-trade policy in favor of a free-trade policy. If, as a result, the domestic price of pistachios decreases to equal the world price of pistachios, then
A.
that country becomes an importer of pistachios.
B.
that country has a comparative advantage in producing pistachios.
C.
at the world price, the quantity of pistachios supplied in that country exceeds the quantity of pistachios demanded in that country.
D.
All of the above are correct.
【判断题】“东则渔阳 , 上古,西则大同以南奔峰来趋,北尽浑源 , 云中之景 ......”是明代乔宇《 华山记 》中的描写。( ) 错
【简答题】Suppose m is integer,if a=(4,m), b=(-2m,4),OA→=a+2b,OB→=2a-b, |OA→|=|OB→|, then the area of the △OAB is ___.
【简答题】音的物理属性,即音的四大要素是什么?— ,—,—,—。
【简答题】语音物理属性四要素中,()指声音的强弱,与发音体振动幅度的大小有关。