Chao et al. (2015) pointed out that "it is difficult to ensure that students had truly previewed the video" (p. 524).
Also, it is difficult to ensure maximal permissivity with respect to multiple behavioral specifications.
It is difficult to ensure that construction can meet the design parameters.
However, it is difficult to ensure that an oral preparation disintegrates specifically in the human colon.
However, it is difficult to ensure the good lubrication for water-lubricated stern tube bearings under low speed working conditions.
Yet, it is difficult to ensure that participants will be able to sustain their businesses and anticipate their mentorship needs after the programming ends.
But he added: "We all have to admit that it is difficult to ensure the Thai seafood industry's supply chain is 100% clean".
It is difficult to ensure patients complete treatment, with a risk of even transmitting a super bug to their close relatives and friends.
It is difficult to ensure robustness and accuracy when the traditional morphological method (TMM) is used to detect weld feature points, especially in an environment with a strong arc light and splash interference.
However, for complex processes, the manual specification of the appropriate intervention processes at design time can be particularly time-consuming and error-prone, while it is difficult to ensure that all important intervention cases are taken into account.
During the start-up process, the operation parameters are off-designed, the multi-transient phenomenon is inevitable and the intensive emission always appears during varying working condition, it is difficult to ensure the operator of the real power plant to start up the boiler following the design curve.
