This is level 5 of the B-Tunnel.
Use the Runner and the Lizard to do high jumps and cross the gaps, and you may need to change gravity in midair sometimes. You may need to run on the crumbling tiles, so you need to act faster-than-normal. But, never panic. This makes you lose the level.
Alternatively, you can get the Child. He can run over the crumbling tiles without toppling them, which reduces the difficulty of this level considerably.