Having finished her project, she was invited by the school     to the new students.

A．speaking

B．having spoken

C．to speak

D．to have spoken

关于人体组织和体液的回声强度说法，不正确的是

A．一般分为高、中、低、无四级
B．介于两级之间的回声可用“中高回声”和“中低回声”表示
C．可在高回声和低回声之前加用形容词
D．强回声后一定有声影
E．典型的中等回声水平见于肝脾实质