--I don’t have a partner to practice English_____.

--Why not join an English language club to practice_____?

A．/; speaking

B．with; to speak

C．/; to speak

D．with; speaking

同一支密度计依次放在三种不同液体中，如图所示，则密度计所受浮力F_A_____F_B_____F_C；三种液体的密度关系是ρ_A_____ρ_B_____ρ_C．