【简答题】任务型阅读。 Almost everyone likes to travel. People can travel by car, bus, train or airplane. When they go to other countries, people usually travel by plane. People travel for different reasons. But no m...
【简答题】观察下列等式: 2 1 +2=4; 2 1 ×2=4; 3 2 +3= 9 2 ; 3 2 ×3= 9 2 ; 4 3 +4= 16 3 ; 4 3 ×4= 16 3 ;…,根据这些等式反映的结果,可以得出一个关于自然数n的等式,这个等式可以表示为______.
【简答题】观察下面计算: 情形1:2× 2 1 =4,2 + 2 1 =4; 情形2:3× 3 2 = 9 2 ,3+ 3 2 = 9 2 ;情形3:4× 4 3 = 16 3 ,4+ 4 3 = 16 3 ;… (1)根据上述规律,写出情形n; (2)根据共同特征,写出你的猜想,并证明你的猜想的正确性.
【简答题】简述配制标准溶液的两种方法。下列物质中哪些可用直接法配制标准溶液?哪些只能用间接法配制? NaOH,H2SO4,HCl,KMnO4,K2Cr2O7,AgNO3,NaCl,Na2S2O3。
【简答题】简述配制标准溶液的两种方法。下列物质中哪些可用直接法配制标准溶液?哪些只能用间接法配制? NaOH,H 2 SO 4 ,HCl,KMnO 4 ,K 2 Cr 2 O 7 , AgNO 3 ,NaCl,Na 2 S 2 O 3 。
【判断题】拥有规模经济的厂商不一定拥有范围经济,拥有范围经济的厂商也不一定拥有规模经济。
【简答题】When people travel in another city or country ,they sometimes stay in the homes of the local people. This is called homestay . It is a great experience because you can me...