It has been difficult to achieve on smartphones because of hardware limitations.
These objectives have been difficult to achieve given the popularity and proliferation of competing programs from the United States.
To be totally effective these schemes need complete public cooperation, a requirement that has been difficult to achieve.
But they go on to say: "Mitigation, although technologically feasible, has been difficult to achieve for political, economic, and social reasons that may persist well into the future..
But its English-language dialogue also allowed its sale to film distributors in 20 countries, which would have been difficult to achieve with a French-language film.
An agreement might have been difficult to achieve under any circumstances; as it was, the negotiations took place during a period of extraordinary political turmoil in Pakistan.
But unity has been difficult to achieve in this Gulf kingdom, which has been split apart by a year-long protest seeking greater political freedom for Shiites.
However, review of this kind has been difficult to achieve.
Yet, in spite of this, systematic reuse in practice has been difficult to achieve.
Control of dengue has been difficult to achieve because of some reasons.
Historically, this has been difficult to achieve due to lack of emergency surgical resources.
