複選題18.Concerning the statem nents of RNA and DNA which is/are CORRECT? (A) The molecular weight of a single-stranded (Ss) RNA is lighter than that of ssDNA with the same length(B) mRNA is more stable than double-s stranded DNA (C) The sugar in DNA and RNA is a pentose (D) Compare to dsDNA, mRNA tends to form secondary structure (E) mRNA is more abund dant than rRNA and tRNA in a cell