河海大学研究生生科协以“（）”为宗旨，促进广大研究生同学崇尚科学、勇于创造、努力学习、奋发成才。

A. echo The current working path is $PW
B. echo "The current working path is $PW" Echo hello
C. echo 'The current working path is $PW' Echo hello
D. echo "The current working path is `pwd`."
E. echo The current working path is $PWEcho hello

A. 要约邀请
B. 要约准备
C. 要约
D. 承诺