pass muster as sth
meaning be accepted as good enough for sth. [1]
e.g., I hope I'll be pass muster as a candidate for software engineer.
PS: pass verb; muster N-count.
step into the breach
meaning help by doing someone else' job or work when they are unable to do it.
take the floor
take (to) the floor (=begin dancing)
take the floor == begin speaking at an important public meeting.
e.g., Once I take the floor, I feel nervous.
参考资料
[1] 朗文词典第五版（Longman dictionary） https://www.ldoceonline.com/
