20 g氢氧化钠固体溶于水,配制500mL溶液,该溶液的物质的量浓度为[ ]
A、1.0mol/L
B、0.5mol/L
C、20mol/L
D、0.04mol/L
答案:A
CCTV手机电视收费业务有哪些收费方式?
He was _____ tired _______ he fell asleep as soon as he lay down. [ ]
A. so; that
B. too; to
C. enough; to
D. such; that