下列说法中正确的是(　　)

A．在Na₃PO₄溶液中，c(Na^＋)是c(PO₄^3－)的3倍

B．pH为3的盐酸中，其c(H^＋)是pH为1的盐酸中c(H^＋)的3倍

C．0.1 mol·L^－1KOH溶液和0.1 mol·L^－1氨水中，其c(OH^－)相等

D．在25℃时，无论是酸性、碱性还是中性的稀溶液中，其c(H^＋)和c(OH^－)的乘积都等于1×10^－14

Just now, I entered the website “Topic for Today”. I feel interested in the report on middle school students’ 小题1:_________(use) cell-phones on campus. In fact, more students now come to school with cell-phones. My schoolmates have different opinions. 小题2:_________ think it is convenient to get in touch 小题3:_________others with the cell-phone, 小题4:_________also makes you feel safe especially in time of trouble. Besides it is nice to enjoy various functions of different cell-phones. Others think differently. 小题5:_________, the cell-phone is not 小题6:_________ must in school, as there are some IC phones, making 小题7:_________ easy to call others. Second, many students often play e-games and send e-massages with their cell-phones, even in class, which will surely have bad effects 小题8:_________ their study. What’s more, it will result 小题9:_________ in a great waste of time and money. In my opinion, the cell-phone is a useful tool in our daily life. But it doesn’t mean we can use 小题10:_____ (free) in school.