1.   The experiment went wrong when the chemicals combined to form a poisonous gas.

2.   When the two chemicals combine, they form an explosive compound.

3.   The chemicals combine instantly to become a powerful irritant, spurting out as hot as boiling water.

4.   The chemicals can combine with the water to produce a toxic reaction.

5.   A somewhat similar poison-gas device was found in a Shinjuku restroom exactly one month ago, also before its chemicals could combine.

6.   Exactly one month earlier, a similar poison-gas device was found in a Shinjuku restroom, also before its chemicals could combine.

7.   Police suspect someone lit the fire, which could cause the chemicals to combine and produce the deadly vapor, reports said.

8.   Station workers doused the flames before the chemicals could combine.

9.   The chemicals combined with the stronger sunlight of spring and very low temperatures in the lower stratosphere to destroy ozone, the agency said.