【2020最新整理国开(电大)人文英语1-3896网上形考机考题库】Tom is good at playing ________ piano.

【2020最新整理国开(电大)人文英语1-3896网上形考机考题库】Tom is good at playing ________ piano.
选择一项：
A. a
B. an
C. the