Collaboration in study groups is a huge part of surviving Harvard's ___________(繁重的学习负担).
The school's faculty and students chose Obama to be their commencement speaker to _______(开始) their 50th anniversary celebration.
I slipped back inside the house and just walked through the rooms for no reason ________(尤其、特别).
In an age of information explosion, it is vital to _________(整理、分类) masses of sources and select what is needed.