声音在15℃空气中的传播速度是 m/s，人面对山谷对面的山峰喊一声，2s后听到回音，则人与山峰之间的距离大约是 m。
340，340
My sister was against my suggestion while my brother was ______ it. [ ]
A. in favour of
B. in memory of
C. in honour of
D. in search of
既受正反馈调节的影响又受负反馈调节影响
A．甲状旁腺素分泌B．催产素分泌C．雌激素分泌D．胰岛素分泌
