A.點(diǎn)到點(diǎn)實(shí)時(shí)應(yīng)用 B.點(diǎn)到點(diǎn)非實(shí)時(shí)應(yīng)用 C.點(diǎn)到多點(diǎn)實(shí)時(shí)應(yīng)用 D.點(diǎn)到多點(diǎn)非實(shí)時(shí)應(yīng)用