若BaCl2中含有NaCl、KCl、CaCl2等杂质,用H2SO4沉淀Ba2+时,生成的BaSO4最易吸附何种离子? ( )
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
免费的网站请分享给朋友吧