are---> is.

Do chủ ngữ ( Mrs Phuong) là số ít.

Câu trả lời đây bạn nhé ^^

http://olm.vn/hoi-dap/question/602523.html

Ta có:

\(\frac{1}{2}=\frac{1}{2}\)

\(\frac{1}{3}+\frac{1}{4}>\frac{1}{4}+\frac{1}{4}=\frac{1}{2}\)

\(\frac{1}{5}+...+\frac{1}{8}>4.\frac{1}{8}=\frac{1}{2}\)

\(\frac{1}{9}+...+\frac{1}{16}>8.\frac{1}{16}=\frac{1}{2}\)

\(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{16}>4.\frac{1}{2}=2\)

\(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{63}>\frac{1}{2}+\frac{1}{3}+...+\frac{1}{16}\)

\(\Rightarrow\frac{1}{2}+\frac{1}{3}+...+\frac{1}{63}>2\)